Here is what I have:

1990 5.0 TPI

The car ran fine until I did the following work:

• Replaced plug wires, distributor cap, rotor.
• Removed and cleaned plenum and throttle body with LOTS of solvent; installed new gaskets
• Sprayed down engine with degreaser

When I first start and drive the car, it starts and idles better than ever. Smooth idle and plenty of power.

However, once it reaches operating temperature, it will start to die when idling (a sudden --it doesn't gradually die--it cuts off when idling at 800-ish and immediately goes to zero RPM).

This gets progressively worse over the next few minutes, until I can't keep it running at less than 2500 RPM.

If I let it cool down, it will starts immediately and runs well...until it gets warm...then the cycle starts all over again.

I have triple checked all vacuum hoses--replaced any that looked bad and looked around for anything that might be disconnected.

WHAT could this be? Please help!

 

I don't know ... but I'm interested to see the answer to this. Sorry I couldn't be any help.

 

.

 

i had a similar problem, egr valve stuck open, it would cause a big drop in vacuum and the vehicle wouldnt run, could check your vacuum and see if it drops below 2000rpms, if so it may be the egr being stuck open, above idle its open anyways so you wouldnt see a difference

 

Update...

I cleaned the heck out of the IAC, let the car run for 10 minutes and it returned to normal idle...

I don't know if this because the computer needed to reset itself after being disconnected and the plenum, etc being soaked in carb cleaner or if all the gunk in the TB had just run down onto the IAC and gunked it up...